diff --git a/openhands/utils/http_session.py b/openhands/utils/http_session.py
index 9421d19dbb..cf95a35879 100644
--- a/openhands/utils/http_session.py
+++ b/openhands/utils/http_session.py
@@ -1,6 +1,8 @@
 from dataclasses import dataclass, field
+from typing import Any, cast
 
 import requests
+from requests.structures import CaseInsensitiveDict
 
 from openhands.core.logger import openhands_logger as logger
 
@@ -15,13 +17,25 @@ class HttpSession:
 
     session: requests.Session | None = field(default_factory=requests.Session)
 
-    def __getattr__(self, name):
+    def __getattr__(self, name: str) -> Any:
         if self.session is None:
             logger.error(
                 'Session is being used after close!', stack_info=True, exc_info=True
             )
-        return object.__getattribute__(self.session, name)
+            raise RuntimeError('Session is being used after close!')
+        return getattr(self.session, name)
 
-    def close(self):
+    @property
+    def headers(self) -> CaseInsensitiveDict[str]:
+        if self.session is None:
+            logger.error(
+                'Session is being used after close!', stack_info=True, exc_info=True
+            )
+            raise RuntimeError('Session is being used after close!')
+        # Cast to CaseInsensitiveDict[str] since mypy doesn't know the exact type
+        return cast(CaseInsensitiveDict[str], self.session.headers)
+
+    def close(self) -> None:
         if self.session is not None:
             self.session.close()
+            self.session = None
diff --git a/openhands/utils/prompt.py b/openhands/utils/prompt.py
index 7fc5d46382..47123345ad 100644
--- a/openhands/utils/prompt.py
+++ b/openhands/utils/prompt.py
@@ -109,7 +109,7 @@ class PromptManager:
                 if name not in self.disabled_microagents:
                     self.repo_microagents[name] = microagent
 
-    def load_microagents(self, microagents: list[BaseMicroAgent]):
+    def load_microagents(self, microagents: list[BaseMicroAgent]) -> None:
         """Load microagents from a list of BaseMicroAgents.
 
         This is typically used when loading microagents from inside a repo.
@@ -135,7 +135,7 @@ class PromptManager:
     def get_system_message(self) -> str:
         return self.system_template.render().strip()
 
-    def set_runtime_info(self, runtime: Runtime):
+    def set_runtime_info(self, runtime: Runtime) -> None:
         self.runtime_info.available_hosts = runtime.web_hosts
 
     def set_repository_info(
diff --git a/openhands/utils/shutdown_listener.py b/openhands/utils/shutdown_listener.py
index eddaac54f0..ac99094ce6 100644
--- a/openhands/utils/shutdown_listener.py
+++ b/openhands/utils/shutdown_listener.py
@@ -19,10 +19,10 @@ _should_exit = None
 _shutdown_listeners: dict[UUID, Callable] = {}
 
 
-def _register_signal_handler(sig: signal.Signals):
+def _register_signal_handler(sig: signal.Signals) -> None:
     original_handler = None
 
-    def handler(sig_: int, frame: FrameType | None):
+    def handler(sig_: int, frame: FrameType | None) -> None:
         logger.debug(f'shutdown_signal:{sig_}')
         global _should_exit
         if not _should_exit:
@@ -39,7 +39,7 @@ def _register_signal_handler(sig: signal.Signals):
     original_handler = signal.signal(sig, handler)
 
 
-def _register_signal_handlers():
+def _register_signal_handlers() -> None:
     global _should_exit
     if _should_exit is not None:
         return
@@ -66,7 +66,7 @@ def should_continue() -> bool:
     return not _should_exit
 
 
-def sleep_if_should_continue(timeout: float):
+def sleep_if_should_continue(timeout: float) -> None:
     if timeout <= 1:
         time.sleep(timeout)
         return
@@ -75,7 +75,7 @@ def sleep_if_should_continue(timeout: float):
         time.sleep(1)
 
 
-async def async_sleep_if_should_continue(timeout: float):
+async def async_sleep_if_should_continue(timeout: float) -> None:
     if timeout <= 1:
         await asyncio.sleep(timeout)
         return
diff --git a/openhands/utils/tenacity_stop.py b/openhands/utils/tenacity_stop.py
index d9aa83a613..d877c1f27e 100644
--- a/openhands/utils/tenacity_stop.py
+++ b/openhands/utils/tenacity_stop.py
@@ -8,4 +8,4 @@ class stop_if_should_exit(stop_base):
     """Stop if the should_exit flag is set."""
 
     def __call__(self, retry_state: 'RetryCallState') -> bool:
-        return should_exit()
+        return bool(should_exit())